Chemistry 9th Chap 5 : Topic 6 - Maryam Publications

Chemistry Chapter 5 : Topic 6

Bonding and Properties

1 / 15

A student observes that sodium chloride forms hard crystals and melts only at very high temperature. Which explanation best describes this property based on its bonding and structure?

A) Sodium chloride consists of atoms connected through weak covalent interactions.

B) Sodium chloride contains weak intermolecular forces that require large heat energy to overcome.

C) Sodium chloride has a giant lattice of oppositely charged ions held together by strong electrostatic attractions.

D) Sodium chloride contains neutral molecules that are tightly packed but weakly bonded.

2 / 15

Magnesium oxide (MgO) has a much higher melting point than carbon dioxide (CO₂). Which structural difference best explains this observation?

A) MgO contains small molecules while CO₂ forms a giant lattice.

B) MgO contains ionic bonds forming a strong lattice whereas CO₂ consists of discrete covalent molecules.

C) CO₂ molecules attract each other through strong ionic forces.

D) MgO molecules are larger than CO₂ molecules.

3 / 15

Diamond and graphite are both forms of carbon but show very different physical properties. Which statement best explains this difference?

A) Diamond has a three-dimensional covalent network while graphite has layered structures with weak forces between layers.

B) Graphite has no covalent bonds between carbon atoms.

C) Diamond contains ionic bonds while graphite contains metallic bonds.

D) Diamond molecules are smaller than graphite molecules.

4 / 15

A compound conducts electricity when dissolved in water but does not conduct electricity in solid form. Which explanation best describes this behavior?

A) The compound breaks into atoms when dissolved in water.

B) The ions in solid form are fixed in position but become mobile in aqueous solution.

C) The compound forms molecules only when dissolved.

D) The compound contains free electrons only in liquid state.

5 / 15

Which property is most characteristic of compounds that consist of simple covalent molecules?

A) Formation of a giant ionic lattice

B) Very high melting and boiling points

C) Ability to conduct electricity in solid state

D) Low melting and boiling points due to weak intermolecular forces

6 / 15

Silicon dioxide (SiO₂) has a very high melting point and does not conduct electricity. Which structural feature explains these properties?

A) It has a giant covalent network where atoms are strongly bonded in a three-dimensional structure.

B) It consists of small molecules with strong intermolecular forces.

C) It forms ionic bonds between silicon and oxygen.

D) It contains mobile electrons similar to metals.

7 / 15

A substance is soft and slippery and can conduct electricity. Its structure consists of layers of atoms with weak forces between layers. Which structure best explains these properties?

A) Metallic lattice

B) Ionic lattice

C) Molecular covalent structure

D) Layered covalent structure

8 / 15

Why do ionic compounds generally dissolve well in water?

A) Polar water molecules attract and separate ions in the lattice.

B) Water weakens metallic bonding.

C) Water reacts chemically with ionic compounds to form molecules.

D) Water molecules break covalent bonds within molecules.

9 / 15

Which property distinguishes giant covalent structures from ionic compounds?

A) Formation of crystal lattice

B) Lack of mobile charged particles

C) High melting points

D) Strong bonds between atoms

10 / 15

A compound has the following properties: low boiling point, does not conduct electricity, and exists as gas at room temperature. Which bonding type is most likely present?

A) Simple covalent bonding

B) Metallic bonding

C) Ionic bonding

D) Giant covalent bonding

11 / 15

Why are ionic crystals usually brittle?

A) The ions can move freely within the lattice.

B) Ionic compounds consist of neutral molecules.

C) Ionic compounds contain weak covalent bonds.

D) When layers shift, like charges come close and repel strongly.

12 / 15

Which factor mainly determines the physical properties of a compound such as melting point and electrical conductivity?

A) Colour of the compound

B) Shape of the container

C) Type of bonding and arrangement of particles

D) Atomic mass of elements

13 / 15

Which statement best explains why methane (CH₄) has a much lower boiling point than sodium chloride (NaCl)?

A) Methane contains ionic bonds while NaCl contains covalent bonds.

B) Methane molecules are larger than NaCl units.

C) Methane contains metallic bonding.

D) Methane contains weaker intermolecular forces compared to strong ionic attractions in NaCl.

14 / 15

Which compound is most likely to have a giant covalent structure?

A) Carbon dioxide

B) Silicon dioxide

C) Hydrogen chloride

D) Methane

15 / 15

A chemist states that the structure of a compound is responsible for its hardness, melting point, and electrical behavior. Which example best supports this statement?

A) Sodium chloride is soft because it contains ions.

B) Methane is solid because its molecules are tightly bonded.

C) Oxygen conducts electricity because it contains atoms.

D) Graphite is soft despite strong covalent bonds due to its layered structure.

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